Source : Webster's Revised Unabridged Dictionary (1913)

Roily \Roil"y\, a.
   Turbid; as, roily water.

Source : WordNet®

roily
     adj : (of a liquid) agitated vigorously; in a state of turbulence;
           "the river's roiling current"; "turbulent rapids" [syn:
            {churning}, {roiling}, {roiled}, {turbulent}]
     [also: {roiliest}, {roilier}]